Looking at the specs from a John K’s bulletin......

They are specs given so someone can test the springs and verify they are still serviceable...... they don’t necessarily tell you what the installed operating loads are.

Unless there is something peculiar to the MW retainer, the typical BB retainer has a nominal .080” step, and the step on the head is usually .100-.120”........ so the inner spring installed height would be a nominal .200” shorter than the outer spring....... if no shims are used on the outer spring.

Calculating the rate from the specs provided, and averaging the mid-point between the hi and low specs....... the outer springs are 342lbs/in, and the inners are 109lbs/in. 451lbs/in for the two combined.

Installed at 1.86 outer/1.66 inner, the loads would be a nominal: 114 closed/340@.500 lift.

For comparison, the MP 933 Hemi spring is rated at 109@1.900, 432lbs/in....... so installed at the same 1.86 as the example above, it would be 126@1.86 and 342@.500 lift.

Unless it’s a numbers matching, nut and bolt type of restoration...... I wouldn’t bother trying to duplicate that OE spring arrangement.
When refurbishing and upgrading OE heads, my preference is to machine down the inner step on the heads and use either a spring cup or inner spring seat , and a spring that’s currently in production and easily replaced if necessary.